E2251. Medical Applications of Mass Spectrometry in Nuclear Medicine and Novel Radiopharmaceuticals
  1. Behnaz Akbari; Boston University
Mass spectrometry (MS) has long-established applications in radiochemistry laboratories, deriving from radiocarbon dating. In medical imaging, the application of radiotracers offers profound insights and makes notable advances in drug discovery and nuclear medicine. All radioactive emissions are detectable by imaging techniques. Likewise, extensive attempts have been made to design radiopharmaceuticals for specific diseases. While positron emission tomography (PET) imaging, in a non-invasive manner, has taken full advantage of MS, and today, newly synthesized radiotracers have been developed for molecular imaging, due to very low doses of the tracers, they cannot induce pharmacological responses. So, those complexes' absorption, distribution, metabolism, and elimination properties may differ after injection at regular therapeutic dosages. However, as an alternative way, mass spectrometry imaging (MSI) can image the distribution of drugs ex vivo and detect the original organic compound and the formation of different metabolites simultaneously. Although MSI cannot obtain the same kinetics and distribution as PET because a higher dose of drug is used for MSI, individual ion images may be generated by MS based on the intensities of the selected compound within the ample surface, without any need for the radio-labeled mixture in a couple of hours.

Educational Goals / Teaching Points
The goal of this presentation is to review mass spectrometry technology, discuss radiopharmaceuticals and their latest advances, development in medical science, and explain medical applications of mass spectrometry (MS) in nuclear medicine.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Describe the applications of mass spectrometry for identification of radiotracers, illustrate tracer properties, binding affinity, kinetics, and uptake, introduce imaging mass spectrometry techniques (e.g., Matrix-Assisted Laser Desorption Ionization (MALDI) and Desorption Electrospray Ionization (DESI) mass spectrometry for biomolecular analysis within the brain tissue slices.

MS can image endogenous targets such as lipids, tissue-specific biomarkers, and exogenous targets, such as drugs and drug metabolites. This presentation emphasizes the application of mass spectrometry in the preclinical design and assessment of novel radiopharmaceutical compounds. Likewise, as new approaches, the medical applications of Matrix-assisted laser desorption electrospray ionization (DESI) and matrix-assisted laser desorption (MALDI) mass spectrometry imaging will be highlighted in this context.